Systems and Methods for Fiber-Coupled Microtip Sensors

Abstract

Systems and methods for fiber optic-coupled microtip sensors are described. Such sensors can be combined with tunable lasers to achieve precision detection of various types of gaseous chemical substances.

What is claimed is: 
     
         1 . A gas sensor, comprising:
 a light source emitting a light;   a first fiber optic connected to the light source, wherein a first end of the first fiber optic is configured to collimate the light;   a second fiber optic with a first end separated by a fixed distance from the first end of the first fiber optic, wherein the collimated light emitted from the first end of the first fiber optic crosses the fixed distance and is received by the first end of the second fiber optic; wherein the light is coupled between the first end of the first fiber optic and the first end of the second fiber optic;   a stabilizing unit configured to hold the first end of the first fiber optic and the first end of the second fiber optic stationary and at the fixed distance to allow the coupling of the light in between; and   a photodetector connected to the second fiber optic, wherein the photodetector measures an optical signal induced by a change in characters of the light in the fixed distance between the first end of the first fiber optic and the first end of the second fiber optic.   
     
     
         2 . The gas sensor of  claim 1 , wherein the light source is a light emitting diode. 
     
     
         3 . The gas sensor of  claim 1 , wherein the light source is a tunable laser. 
     
     
         4 . The gas sensor of  claim 3 , wherein a wavelength or frequency of the tunable laser is tuned to a plurality of resonance lines of the gas. 
     
     
         5 . The gas sensor of  claim 3 , wherein the tunable laser is a part of a laser package. 
     
     
         6 . The gas sensor of  claim 1 , the first fiber optic and the second fiber optic each comprise a fiber optic material that transmits the light. 
     
     
         7 . The gas sensor of  claim 6 , wherein the fiber optic material is selected from the group consisting of: quartz, silica, fused silica, and ZBLAN glass. 
     
     
         8 . The gas sensor of  claim 1 , wherein the first end of the first fiber optic comprises a straight side and a curved side, wherein the straight side collimates the light and the curved side transmits the collimated light to the first end of the second fiber optic. 
     
     
         9 . The gas sensor of  claim 1 , wherein the fixed distance is selected based on a plurality of absorption features of the gas. 
     
     
         10 . The gas sensor of  claim 1 , wherein the fixed distance is greater than or equal to 0.5 mm and less than or equal to 10 mm. 
     
     
         11 . The gas sensor of  claim 1 , wherein the fixed distance is 1 mm. 
     
     
         12 . The gas sensor of  claim 1 , wherein the stabilizing unit comprises a material of a similar coefficient of thermal expansion as the first fiber optic and/or the second fiber optic. 
     
     
         13 . The gas sensor of  claim 1 , wherein the stabilizing unit comprises a material selected from the group consisting of: a nickel-cobalt ferrous alloy, a nickel-iron alloy, Kovar, and Invar. 
     
     
         14 . The gas sensor of  claim 1 , wherein the gas sensor is a portion of a spacesuit or an in-situ resource utilization (ISRU) processing unit. 
     
     
         15 . The gas sensor of  claim 1 , wherein the gas is selected from the group consisting of: carbon dioxide, oxygen, methane, and water vapor. 
     
     
         16 . A method for detecting a gas, comprising:
 measuring a concentration of the gas using a gas sensor, wherein the gas sensor comprises:
 a light source emitting a light; 
 a first fiber optic connected to the light source, wherein a first end of the first fiber optic is configured to collimate the light; 
 a second fiber optic with a first end separated by a fixed distance from the first end of the first fiber optic, wherein the collimated light emitted from the first end of the first fiber optic crosses the fixed distance and is received by the first end of the second fiber optic; wherein the light is coupled between the first end of the first fiber optic and the first end of the second fiber optic; 
 a stabilizing unit configured to hold the first end of the first fiber optic and the first end of the second fiber optic stationary and at the fixed distance to allow the coupling of the light in between; and 
 a photodetector connected to the second fiber optic, wherein the photodetector measures an optical signal induced by a change in characters of the light in the fixed distance between the first end of the first fiber optic and the first end of the second fiber optic; and 
   determining the concentration of the gas based on the optical signal measured by the photodetector.   
     
     
         17 . The method of  claim 16 , further comprises calibrating the gas sensor to a known concentration of the gas. 
     
     
         18 . The method of  claim 16 , wherein the light source is a tunable laser. 
     
     
         19 . The method of  claim 16 , wherein the first fiber optic and the second fiber optic each comprise a fiber optic material that transmits the light; wherein the fiber optic material is selected from the group consisting of: quartz, silica, fused silica, and ZBLAN glass. 
     
     
         20 . The method of  claim 16 , wherein the first end of the first fiber optic comprises a straight side and a curved side, wherein the straight side collimates the light and the curved side transmits the collimated light to the first end of the second fiber optic. 
     
     
         21 . The method of  claim 16 , wherein the fixed distance is greater than or equal to 0.5 mm and less than or equal to 10 mm. 
     
     
         22 . The method of  claim 16 , wherein the stabilizing unit comprises a material selected from the group consisting of: a nickel-cobalt ferrous alloy, a nickel-iron alloy, Kovar, and Invar.